[GHC] #11706: Increase precedence of lexps (if-then-else, case-of, do, lambda and let-in)

[GHC]

#11706: Increase precedence of lexps (if-then-else, case-of, do, lambda and let-in)
-------------------------------------+-------------------------------------
        Reporter:  YoYoYonnY         |                Owner:
            Type:  feature request   |               Status:  infoneeded
        Priority:  lowest            |            Milestone:  ⊥
       Component:  Compiler          |              Version:
  (Parser)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Description changed by YoYoYonnY:

@@ -16,1 +16,1 @@
- Basically, these are the rule Haskell already uses.
+ Basically, these are the rules Haskell already uses.
@@ -30,3 +30,3 @@
- [https://ghc.haskell.org/trac/ghc/ticket/10843#comment:12 in this
- comment]); combining {{{lexp}}} with {{{aexp}}} would make the Haskell
- syntax more consistent.
+ [https://ghc.haskell.org/trac/ghc/ticket/10843#comment:12 this comment]);
+ combining {{{lexp}}} with {{{aexp}}} would make the Haskell syntax more
+ consistent.
@@ -71,0 +71,1 @@
+
@@ -72,0 +73,1 @@
+
@@ -74,0 +76,1 @@
+

New description:

 == Intro ==

 For readability, the intro is now available [http://pastebin.com/8Fsh7pAE
 here].

 == How it works ==

  * Implicit parenthesis will be put around ''all'' {{{lexps}}}, according
 to the following rules:
   1. Parenthesis will be opened at the start of the {{{lexp}}}.
   2. Parenthesis will be closed at the end of the {{{lexp}}}. The end of
 the {{{lexp}}} is determined by
    1. The curly brackets around the {{{lexp}}} (If possible), or;
    2. The indentation of the {{{lexp}}}

 Basically, these are the rules Haskell already uses.

 As for the Context-Free Syntax found at
 https://www.haskell.org/onlinereport/haskell2010/haskellch10.html#x17-17800010.3|layout,
 {{{lexp}}} would have to be moved up, dropped out of {{{infixexp}}}, and
 added into {{{exp}}} (As well as a few other places in {{{aexp}}} and
 {{{guard}}})

 == Motivation ==

 As for my personal motivation, I think that, with all the other syntactic
 extensions already implemented, this feature is definitly missing.

 As Richard Eisenberg already pointed out (See
 [https://ghc.haskell.org/trac/ghc/ticket/10843#comment:12 this comment]);
 combining {{{lexp}}} with {{{aexp}}} would make the Haskell syntax more
 consistent.

 bgamari listed above argument and quite a few other pros and cons
 [https://ghc.haskell.org/trac/ghc/ticket/10843#comment:12 here].

 A few arguments not listed there:

  * If the Haskell community ever decides to implement this feature in the
 main language, we will already be prepared.
  * Similairly, if this feature ever gives problems or adds new interesting
 possibilities to the language, we will be prepared.
   * Yet another syntactical extension means yet another thing to look out
 for;
   * However, this also means people will become more aware of LANGUAGE
 pragmas.

 == Naming ==

 Here follow a few suggestions for the name of this extension:

  * InlineStatements
  * InfixStatements
  * ParenthesizedStatements
  * IncreasedStatementPrecedence
  * StatementsWithoutParenthesis

 Here are some more, taken from [https://mail.haskell.org/pipermail
 /haskell-cafe/2015-September/121217.html over here].

  * ArgumentBlock
  * ArgumentDo

 == Examples ==

 Examples can now be found [http://pastebin.com/6kLQvKs9 here].

 == Resources ==

 [1] Cheesy intro: http://pastebin.com/8Fsh7pAE

 [2] Original examples: [http://pastebin.com/6kLQvKs9]

 [3] Pros and Cons:
 [https://ghc.haskell.org/trac/ghc/ticket/10843#comment:12]

 [4] ArgumentBlock proposal: [https://mail.haskell.org/pipermail/haskell-
 cafe/2015-September/121217.html]

--

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11706#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler